STI STI-3350 Wireless Doorbell Chime Receiver
Overview
The STI-3350 is a wireless chime receiver that retrofits existing hardwired doorbell systems without requiring new wiring to the monitoring station. Paired with the STI-3331 Wireless Doorbell Extender Sensor (mounted at the doorbell box), the STI-3350 receives doorbell presses up to 500 feet away (line of sight) — solving the common problem of monitoring stations or security offices too distant from front entrances to hear a traditional chime. The receiver plugs into any standard 120 VAC outlet; once the sensor is installed on the doorbell terminals, wireless notification is active immediately. This approach preserves the original doorbell functionality while adding wireless reach without cutting or reconnecting wires.
Key Features
- 433 MHz FCC/IC Certified Wireless: Uses a licensed frequency with FCC and IC certification — ensures reliable, non-interfering signal. No consumer Wi-Fi congestion, no Bluetooth dropouts at distance. The protocol is designed for door access and perimeter applications.
- 500-Foot Line-of-Sight Range: Clear path between sensor and receiver yields maximum distance. Walls, metal studs, and dense materials reduce range; account for building penetration when positioning the receiver. Sufficient for most office buildings, warehouses, and multi-tenant facilities where the entrance is separated from the security desk by a floor or two.
- Dual Tone Alerts (Front and Rear Doorbells): Front doorbell triggers a "ding-dong" tone; rear doorbell (if wired) produces a "ding" tone — distinct audio cues allow staff to differentiate entry points without looking at a status display. Tones are fixed and cannot be reprogrammed.
- Low and High Volume Settings: Receiver volume is adjustable to match acoustic environment — loud enough to hear in a busy control room, low enough not to distract in quiet offices. No remote volume control; adjustment is manual on the unit itself.
- Non-Intrusive Sensor Installation: The STI-3331 sensor mounts via double-sided tape and fork-shaped connectors that slide onto existing doorbell terminal screws (Brown, Black, Red connections per 433 MHz standard). Original doorbell wiring remains untouched. No splicing, no desoldering, no risk of damaging the existing circuit. If a rear doorbell is absent, the brown wire connector is simply taped back and left disconnected.
- 120 VAC Plug-and-Play Receiver: The STI-3350 draws power from a standard outlet — no batteries, no hardwiring, no need for an electrician. Receiver can be relocated to different outlets if monitoring coverage patterns change. Pairing with the sensor is initiated by pressing the receiver's pairing button, then triggering the doorbell; the wireless link establishes within seconds.
Integration & Compatibility
The STI-3350 works exclusively with the STI-3331 Wireless Doorbell Extender Sensor. The sensor must be mounted inside or outside the existing house doorbell box and taps into the doorbell's front and rear terminals. The system does not integrate with VMS platforms, access control panels, or smart-home hubs — it is a standalone wireless notification device. If you need doorbell events logged into a security system, the receiver's audio output can be monitored by a staff member or integrated into a broader facility announcement system, but there is no native API or contact closure output for alarm panel integration.
Installation Prerequisites
The existing doorbell circuit must be de-energized at the circuit breaker before mounting the sensor to avoid shock. After sensor installation and power restoration, the receiver enters pairing mode via its button and binds to the sensor on first doorbell press. Line-of-sight distance assumes a clear, unobstructed path; walls, metal frames, and structural materials will reduce effective range — test range in your facility before final placement. The receiver's low and high volume settings compensate for different acoustic environments; place it where staff can hear alerts consistently.
What's in the Box
- 1x STI-3353 Chime Receiver
- 1x Power cord for 120 VAC outlet connection
- Pairing instructions (printed)
Frequently Asked Questions
Q: Does the STI-3350 work with smart phones or mobile apps?
A: No. The STI-3350 is a standalone wireless chime receiver. It does not connect to Wi-Fi, Bluetooth, or any app. Alerts are audio-only, heard at the physical receiver unit.
Q: Can I use the STI-3350 without the STI-3331 Sensor?
A: No. The receiver pairs exclusively with the STI-3331 Wireless Doorbell Extender Sensor. The sensor must be mounted at the doorbell to capture the button press and transmit wirelessly to the receiver.
Q: What happens if walls or metal interfere with the 500-foot range?
A: The 500-foot range is specified for line-of-sight conditions (clear, unobstructed path). Walls, metal studs, concrete, and dense materials reduce range significantly. You should test the actual range in your building before deploying. If the distance exceeds the effective wireless reach, consider repositioning the receiver to a location with a clearer line of sight to the sensor, or mount an additional receiver.
Q: Can the doorbell tones be customized or silenced?
A: No. Front doorbell produces a fixed "ding-dong" tone and rear doorbell (if present) produces a fixed "ding" tone. Tones cannot be customized, recorded, or silenced—only the volume (low or high) can be adjusted on the receiver unit.
Q: Is the STI-3350 waterproof or rated for outdoor use?
A: The receiver is designed for indoor 120 VAC outlet use and is not waterproof. It should not be exposed to rain, high humidity, or temperature extremes. The STI-3331 Sensor can be mounted outside the doorbell box, but the receiver must remain in a dry, climate-controlled environment.
Q: What is the warranty on the STI-3350?
A: The STI-3350 comes with a one-year limited manufacturer warranty covering defects in materials and workmanship.
The STI-3350 solves a real problem: existing doorbell circuits buried in old buildings where the entrance is three floors or two wings away from the security desk. Rather than pull new conduit or hardwire a chime extension, the STI-3350 and its companion sensor (STI-3331) retrofit the existing doorbell in under an hour. The 433 MHz wireless link is rock-solid for perimeter notifications—no consumer Wi-Fi interference, no Bluetooth dropout at distance. The real question when evaluating the STI-3350 is whether 500 feet (line of sight) covers your facility's geometry.
Technical Highlights:
- 433 MHz FCC/IC Certified Frequency: Licensed industrial frequency, not subject to Wi-Fi or Bluetooth congestion. Frequency was chosen specifically for door and perimeter alerting—thousands of access control and doorbell systems rely on it. Your signal will not compete with office Wi-Fi or smartphones.
- 500-Foot Nominal Range (Line of Sight): Achieved in clear conditions. Multi-story buildings, concrete walls, and metal studs reduce usable range to 150–300 feet in practice. Before final placement, physically test the link between your planned sensor location and receiver location. If range falls short, relocate the receiver toward an interior wall or corridor that offers clearer sight lines to the doorbell sensor.
- Dual-Tone Audio Differentiation (Front and Rear Doorbells): "Ding-dong" for front entry, "ding" for rear—staff learns which door was pressed without looking away from their work. This is not a trivial feature in busy environments where multiple entrances feed into one monitoring station.
Deployment Considerations:
- Installation requires circuit de-energization at the breaker. The STI-3331 sensor uses non-invasive fork connectors that slide onto existing terminal screws—no wire splicing, minimal downtime. If your doorbell circuit is old or poorly labeled, identify the correct breaker before you start.
- The receiver has no battery backup and no contact closure output. Audio alerts only—if you need the doorbell press logged to an access control panel or security system, you will have to integrate the receiver's audio output into a broader announcement system or monitor it manually. The STI-3350 is not designed for integration with VMS platforms or smart-home hubs.
The STI-3350 is the right pick for retrofit installations where existing doorbell wiring is already in place and the monitoring station is distant from the entrance. It is not suitable for new construction (hardwire a chime instead) or facilities where doorbell events must trigger automated workflows or system-wide alerts. For warehouse or multi-tenant office environments with older infrastructure and no budget for rewiring, it delivers real value.
